Various micrometer devices are known in the art for performing high precision measurements of workpieces using a handheld mechanism. For example, U.S. Pat. Nos. 1,132,704; 3,849,890; 4,485,556; 4,561,185; and 8,091,251 (referred to herein as the '704, '890, '556, '185, and '251 patents), each of which is hereby incorporated by reference in its entirety, disclose micrometer devices. In particular, modern micrometers such as that disclosed in U.S. Pat. No. 5,495,677 (the '677 patent), which is hereby incorporated by reference in its entirety, comprise a linear digital sensor for determining measurements, rather than relying on accurate micrometer threads in combination with a rotary position sensing device. Using a linear digital sensor eliminates the need to use accurate or fine pitch threads in order to drive the micrometer.
Various methods are known for providing constant force in hand measurement tools. For example, U.S. Pat. No. 4,035,922 (the '922 patent), which is hereby incorporated by reference in its entirety, discloses a digital micrometer or gauge which includes a constant force spring to drive two anvils toward each other. However, this particular arrangement is bulky and prone to a potentially short lifetime. Furthermore, if this design were to be more compact, the constant force spring may not provide enough force to properly drive the anvils toward each other.